Explore our comprehensive guide featuring 50 essential C++ interview questions and expertly crafted answers. Whether you're a beginner or an experienced developer, this resource equips you with in-depth knowledge to excel in C++ interviews with the help of these C++ language questions. Master key concepts, coding challenges, and problem-solving techniques to boost your confidence and land your dream job. To make things easier for you, Scholar Hat by Dot Net Tricks brings a comprehensive skill-oriented C++ certification to the nitty-gritty of C++ language.
Standard is another name for "std," or it can be seen as a namespace. The compiler is instructed to add all objects under the std namespace and import them into the global namespace by using the command "using namespace std." Because of the global namespace instillation, we may use "cout" and "cin" instead of "std::_operator_."
A variable becomes an alias of an existing variable when it is described as a reference. To put it simply, a referred variable is a named variable that is another variable that already exists, with the understanding that any changes made to the reference variable would also affect the previously existing variable. A reference variable has a '&' before it.
Example: If "Car" is a class, an object could be a specific car with its unique attributes and behaviours.
Operator overloading in C++ allows defining custom behaviors for operators when used with user-defined classes or data types. It enables objects of a class to behave like built-in types, allowing programmers to provide their implementation of operators such as +, -, *, etc., tailored to specific class instances.
Complex < Complex > real; cout ; cin >> imag; > > >; ; num2.Run Code >>
In this code, the Complex class represents a complex number with real and imaginary parts. The + operator is overloaded inside the class to add two complex numbers. The input() function is used to input complex numbers, and the display() function is used to display the result. When you run the program, it will prompt you to enter the real and imaginary parts of two complex numbers and then display the sum.
Polymorphism in C++ allows objects of different classes to be treated as objects of a common superclass. It enables functions to operate on objects of multiple derived classes through pointers or references to the base class, simplifying code and enhancing flexibility in object-oriented programming.
In C++, a constructor is a special member function with the same name as the class. It is automatically invoked when an object of the class is created. Constructors initialize the object's data members and ensure the object is in a valid state upon creation.
MyClass < << num << ; MyClass obj1; cout ; obj1. cout ; obj2. Run Code >>
In this example, the MyClass class has a default constructor and a parameterized constructor. When objects obj1 and obj2 are created, the constructors are automatically called. The default constructor initializes num to 0, and the parameterized constructor initializes num with the provided value (42 in this case). The display() member function is used to display the values of num for the created objects.
In C++, a reference is an alias for a variable. It allows you to use an existing variable through a different name. References are often used as function parameters to modify variables outside the function or to avoid unnecessary copying of large data structures, enhancing performance and readability.
Any changes we make to the value of ref will show up in x. A reference variable cannot refer to another variable once it has been initialized. An array of references cannot be declared, although an array of pointers may.
In C++, abstraction refers to the concept of hiding complex implementation details and showing only the necessary features of an object. It allows programmers to create user-defined data types and focus on what an object does, rather than how it achieves its functionality, enhancing code simplicity and reusability.
Overloading a destructor is not feasible. There is just one method to delete an object since destroyers don't accept parameters. Destructor overloading is therefore not feasible.
Function overloading and operator overloading are both techniques in C++ to provide multiple definitions for functions or operators, but they differ in their application:
Destructors in C++ are special member functions of a class that are used to clean up resources allocated by objects. They have the same name as the class prefixed with a tilde (~) and are automatically invoked when an object goes out of scope or is explicitly deleted, ensuring proper resource deallocation.
When a class variable is marked static, memory is set aside for it for the duration of the program. There is only one copy of the static member, regardless of how many objects of that class have been produced. This means that all of the objects in that class can access the same static member.
Even in the absence of any class objects, a static member function can still be invoked since it can be reached with just the class name and the scope resolution operator::
In C++, inheritance is a fundamental object-oriented programming concept that allows a class (derived or child class) to inherit properties and behaviors from another class (base or parent class). Derived classes can access public and protected members of the base class, promoting code reusability and establishing a relationship between classes. This mechanism enables the creation of a hierarchy of classes where child classes inherit attributes and methods from their parent, facilitating efficient and organized code development.
While both while and do-while loops in C++ are used for repetitive execution, they differ in their loop control flow:
In C++, prefix and postfix are used to increment or decrement variables. The key differences between them are:
Virtual functions and pure virtual functions are concepts in C++ related to polymorphism and inheritance:
Function overriding in C++ occurs when a derived class provides a specific implementation for a function that is already defined in its base class. To achieve this, the function in the derived class must have the same name, return type, and parameters as the one in the base class. When an object of the derived class calls the overridden function, the derived class's implementation is executed instead of the base class's version, allowing for customization and polymorphic behavior in object-oriented programming.
Multiple inheritance in C++ should be used cautiously and in specific scenarios where it simplifies the design without introducing complexity. It is appropriate when a class needs to inherit properties and behaviors from more than one unrelated class. For example, in GUI frameworks a class may inherit from both a graphical component class and an event handling class. However, it requires careful planning to avoid ambiguity issues, and alternative design patterns like composition or interfaces should be considered to enhance code readability and maintainability.
Virtual inheritance in C++ is a mechanism that prevents multiple instances of a base class in a class hierarchy. It ensures that only one instance of the base class exists when multiple derived classes inherit from it. This prevents issues like the "diamond problem" where ambiguity arises due to multiple inheritance paths.
A virtual destructor in C++ is a destructor declared in the base class with the virtual keyword. When a derived class object is deleted through a pointer to the base class, a virtual destructor ensures that the derived class's destructor is called, preventing memory leaks and ensuring proper cleanup of resources in polymorphic hierarchies.
In C++, the delete operator is used to deallocate memory that was previously allocated using the new operator. It helps free up memory occupied by dynamically allocated objects, preventing memory leaks, and managing resources efficiently during runtime.
delete [] DNT;
In C++, delete and delete[] are used to deallocate memory previously allocated with new and new[] operators, respectively. The key differences are:
Friend class- In C++, a friend class is a class that is granted access to the private and protected members of another class. It is declared using the friend keyword in the class declaration. Friend classes can access private and protected members of the class they are friends with, providing controlled access for specific classes.
Class_1st < Class_2nd; statements; > Class_2nd
Friend function- In C++ Online Compiler, a friend function is a function that is not a member of a class but has access to its private and protected members. It is declared inside the class and can access the class's private and protected data, providing a way to allow external functions special privileges with a specific class.
DNT < statements; OR DNT
Overflow occurs when the value is more than what the data type can handle, an error is produced. Said another way, it's an error type that falls inside the prescribed range but is valid outside of it.
A variable of size 2,247,483,648 will result in an overflow error, for instance, because the range of the int data type is –2,147,483,648 to 2,147,483,647.
In C++, the Scope Resolution operator (::) is used to specify the class or namespace to which a particular identifier (such as a variable or function) belongs. It allows access to class members when there is a naming conflict between local and class-level variables or functions.
In C++, access modifiers control the visibility and accessibility of class members. There are three access modifiers:
Indeed, a program may be compiled without a main() call. For instance, Use Macros that define the main
STL, or Standard Template Library, is a powerful set of C++ template classes and functions that provides general-purpose data structures and algorithms. It simplifies complex tasks, promotes code reuse, and enhances efficiency. STL includes containers, algorithms, iterators, and function objects, making C++ programming more efficient and convenient.
In C++, an inline function is a function that is expanded in place where it is called, instead of being executed through a regular function call mechanism. It is declared with the inline keyword and helps reduce the function call overhead by inserting the function's code directly at the call site.
The answer is No; It cannot be recursive.
An inline function cannot be recursive because it simply loads the code into the location from where it is called, without keeping track of any information on the stack that would be required for recursion.
Additionally, the compiler will automatically disregard an inline keyword placed in front of a recursive function as it only interprets inlines as suggestions.
Use abstract classes when you want to create a common interface for a group of related classes, ensuring that derived classes provide specific implementations for essential methods while allowing for polymorphic behavior.
A class's static data member is a regular data member that is preceded by the term static. When a program runs, it runs before main() and is initialized to 0 upon the creation of the class's first object. Its scope is lifetime, but it is only accessible to a particular class.
The member function that is used to access other static members of the data or other static member functions is known as the static member function. A static keyword is also used to specify it. Either the class name or class objects can be used to access the static member method.
The properties (lifetime and visibility) of a variable or function are defined by the storage class. These properties often aid in tracking a variable's existence while a program runs.
storage_class var_data_type var_name;In C++, there are four primary storage classes, each serving different purposes in controlling the scope, lifetime, and visibility of variables and functions:
Note: The register keyword is deprecated in modern C++ and has limited usage.
As implied by its name, the mutable storage class specifier modifies a class data member only when it is applied to an object that is defined as const, even if the member is a part of the object. Reference, static, or const members can't employ the mutable specifier. This pointer provided to the function becomes const when the function is declared as const.
In conclusion, mastering these top 50 C++ language interview questions is pivotal for aspiring programmers. These insights into fundamental concepts, data structures, and algorithms equip candidates with the knowledge needed to succeed in technical interviews. You can also consider doing our C++ tutorial from Scholar Hat by Dot Net Tricks to upskill your career. Practice, understanding, and confidence in these areas will undoubtedly pave the way to a successful C++ programming career.
To prepare for a C++ programming interview, it's important to have a strong grasp of fundamental concepts such as classes, objects, inheritance, and polymorphism. Additionally, practice solving coding problems, review commonly used C++ libraries and frameworks, and understand advanced topics like smart pointers, move semantics, and multithreading.
In a C++ interview, you can expect a mix of theoretical questions to evaluate your understanding of language features and practical coding problems to assess your problem-solving skills. Questions may cover topics such as memory management, data structures, algorithm design, and the effective use of C++ features like templates and STL containers.
C++ interviews often focus on core concepts such as object-oriented programming (OOP) principles (inheritance, polymorphism, encapsulation), memory management (stack vs. heap), templates, exception handling, standard template library (STL), pointers, references, and operator overloading.
C++ interview questions can range from basic syntax and data types to complex memory management and design patterns. They are typically categorized as:
